1. Field of the Invention
This invention relates in general to certain new and useful improvements in wheelchairs, and more particularly, to improved front wheel assemblies used on wheelchairs.
2. Brief Description of the Prior Art
Wheelchair constructions have remained unchanged, except for relatively minor features, for a substantial period of time. While wheelchairs have existed for many years, they generally were constructed of a main frame, front and rear wheels, side rails or so-called "arm rests" and foot support members.
In recent years, it has been found to be highly beneficial for paraplegics and others required to use wheelchairs on a relatively permanent basis to engage in various forms of athletic activities, including wheelchair racing, tennis, and the like. However, the wheelchair constructions heretofore did not lend themselves to such forms of activities. This was primarily due to the large box-like construction with the high center of gravity in essentially all prior art wheelchairs.
There has been a recent availability of wheelchairs which are effective for use in racing and sports activities. Some of these prior art constructions teach of a selective positioning of a rear wheel so as to alter the center of gravity of the wheelchair by selective positioning of the rear wheel. However, little attention has been paid to the front wheel assemblies, often referred to as "casters" or "front wheel casters" used on these wheelchairs. It has been found in connection with the present invention that the selective positioning of the front wheel can materially affect the overall steering and riding characteristics of the wheelchairs. This is particularly important in racing conditions and sports activities.
It has also been found that when using wheelchairs where the wheels are positioned so that the frame and particularly the seat portion is not horizontally disposed, the user's weight is not evenly distributed from front to rear of the wheelchair, as a result, there is a tendency for the wheelchair to drift, particularly immediately after movement. In other words, in stall conditions, the wheelchair may have a tendency to drift or move around.
It has also been found in connection with the prior art wheelchairs that they are not sufficiently stable when the user is attempting to enter or exit the wheelchair. This is also a problem when a user with a high level back injury is being assisted in entry or exit from the wheelchair.
U.S. Pat. No. 3,893,708 to Moroney discloses a wheel hub and bearing assembly for use with a wheelchair. This assembly is primarily adapted for use on the rear wheels of the wheelchair. Moreover, the construction is quite complex utilizing a plurality of bearing arrangements which thereby substantially increases the overall costs of such a bearing assembly.
U.S. Pat. No. 1,784,330 discloses a wheel retainer which is used with aircraft. This device is designed to prevent displacement of a wheel on the aircraft in the event that the wheel structure breaks and which is also adapted to permit removal of the wheel from the aircraft.
U.S. Pat. No. 4,231,670 to Knoski also discloses a wheel assembly for use with a motor vehicle such as aircraft. This patent discloses a snap/lock pin assembly for releasably mounting a wheel to a vehicle. In this particular case, the wheel may be removed from a heavier axle retaining hub.